Tree Trunk Shakers (TTS) per se, are well known to the art. They consist usually of a vibration-generating element, a pair of jaws to clutch the trunk of a tree, and a supporting arm configured to extend the pair of jaws from a vehicle to the tree. The mechanism of the Tree-Trunk Shaker (TTS) permits the positioning and locking of the jaws on the tree-trunk, and allows the vibration generating element to impose a multi-directional regime of vibrations to the tree. However, since the shaking generated by, the vibration generator is violent and multidirectional, chains and resilient coupling elements are preferably used for connection of the vibration generator to allow movement in all possible directions, thus in all possible degrees of freedom of motion. Evidently, chains provide freedom of motion, even allowing the shaker to be thrown about chaotically. As a result, vibrations are generated in all directions, transmitted, and imparted to the vehicle, with all the detrimental effects on the TTS, on the vehicle and on the driver.
Unwanted vibrations are sometimes accepted as a price to pay against a desired superior result, but in the present case, the efficiency of the TTS is low. Obviously, TTS manufacturers strive to achieve improved tree-fruit harvesting yields, meaning shorter time of tree shaking and greater percentage of harvested fruit.
In U.S. Pat. No. 4,128,986, Santarelli describes a shaker suspended by chains as by column 3, lines 52 to 53: “ . . . fixing point 3 for chains 4 by means of which the vibrating device 1 may be lifted by a tractor 4′, . . . ”. FIG. 1 illustrates the vibrating device as hanging on three separate chains 4 from a supporting arm 5. This mode of suspension is needed since Satarelli wants to, by column 4, lines 66 to 68 “ . . . obtain vibrations the frequency of which is variable during operation substantially through an arc of 360°.” Santarelli believes that multidirectional vibrations are necessary for a TTS, although the harvesting results are poor.
U.S. Pat. No. 4,223,515, invented by Borchard, discloses a “Tree shaker mounting” where the shaker 10 is suspended by a chain 30 and by a rubber block 41, as described in column 2 lines 33 to 34 “ . . . suspended from it is the shaker 30 and a rubber block 41, . . . ”. Borchard too prefers multidirectional shaking, in spite of the inferior harvesting results.
U.S. Pat. No. 4,320,618, by Dandl, deals with, as by the title of the Patent, a “Tree shaker attachment for vehicles” that is “interconnected with the fixed base member 16 by flexible chains 40 in order to better support the tree shaking attachment to the tractor” as in column 3, lines 24 to 26. Dandl is also of the view that, column 1 lines 24 to 27: “ . . . the unidirectional mode of vibration was generally inefficient because of the need for causing relatively violent shaking of the tree.” Therefore, Dandl selects multi-directional shaking, as by column 1 lines 36 to 38 “ . . . for generating a high frequency pulsation, the direction of which changes continuously through an angle of 360° arc, . . . ”. In spite of his efforts, Dandl does not improve harvesting efficiency.
The background art thus professes multidirectional shaking and a freely suspended vibrator as the preferred method of operations for a TTS, even though the harvesting results are far from satisfactory.
There is thus a need for a TTS configured to ascertain optimal results for the fruit-harvesting mission but without imparting vibrations and/or shocks to the harvesting equipment and to the vehicle. Furthermore, there is also a need for the control of the vibration regime to provide not only efficient tree shaking but also overall orchard harvesting performance. In simple words, there is needed an efficient TTS machinery of rigid and robust construction, for delivering shaking vibrations to the tree while isolating the TTS and the vehicle from both shocks and vibrations